|Observation data (J2000 epoch)|
|Right ascension||12h 18m 49.625s|
|Declination||+14° 24′ 59.36″|
|Helio radial velocity||2,404 km/s|
|Distance||45.2 Mly (13.87 Mpc)|
|Group or cluster||Virgo Cluster|
|Apparent magnitude (V)||10.4|
|Apparent size (V)||5.4′ × 4.7′|
|Coma Pinwheel Galaxy, Virgo Cluster Pinwheel, M99, NGC 4254, PGC 39578, UGC 7345|
Messier 99 or M99, also known as NGC 4254, is a grand design spiral galaxy in the northern constellation Coma Berenices approximately 15,000,000 parsecs (49,000,000 light-years) from the Milky Way. It was discovered by Pierre Méchain on 17 March 1781. The discovery was then reported to Charles Messier, who included the object in the Messier Catalogue of comet-like objects. It was one of the first galaxies in which a spiral pattern was seen. This pattern was first identified by Lord Rosse in the spring of 1846.
This galaxy has a morphological classification of SA(s)c, indicating a pure spiral shape with loosely wound arms. It has a peculiar shape with one normal looking arm and an extended arm that is less tightly wound. The galaxy is inclined by 42° to the line-of-sight with a major axis position angle of 68°. Four supernovae have been observed in this galaxy: SN 1967H (type II), 1972Q, 1986I (type II), and 2014L (type Ic).
A bridge of neutral hydrogen gas links NGC 4254 with VIRGOHI21, an HI region and a possible dark galaxy. The gravity from the latter may have distorted M99 and drawn out the gas bridge, as the two galaxy-sized objects may have had a close encounter before parting greatly. However, VIRGOHI21 may instead be tidal debris from an interaction with the lenticular galaxy NGC 4262 some 280 million years ago. It is expected that the drawn out arm will relax to match the normal arm once the encounter is over.
While not classified as a starburst galaxy, M99 has a star formation activity three times larger than other galaxies of similar Hubble type that may have been triggered by the encounter. M99 is likely entering the Virgo Cluster for the first time bound to the periphery of the cluster at a projected separation of 3.7°, or around one megaparsec, from the cluster center at Messier 87. The galaxy is undergoing ram-pressure stripping of much of its interstellar medium as it moves through the intracluster medium.
Image of Messier 99 taken by the NASA/ESA Hubble Space Telescope
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- "A Bright Spark in a Nearby Spiral Galaxy". ESA/Hubble Picture of the Week. Retrieved 4 June 2012.
|Wikimedia Commons has media related to Messier 99.|
- SEDS: Spiral Galaxy M99
- UniverseToday: Dark Matter Galaxy?
- PPARC: New evidence for a Dark Matter Galaxy
- PTF10fqs: A Luminous Red Nova in the Spiral Galaxy Messier 99
- Messier 99 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images